This invention pertains to hydraulic pumps; the invention provides an improved pump and an improved method of manufacturing such pumps. More specifically, our invention is generically applicable to double acting simplex plunger pumps which can be grouped into two categories, i.e., "piston" type. A "plunger" type pump comprises in part a solid plunger which moves or reciprocates relative to a stationary seal. A "piston" type pump comprises in part a piston which moves or reciprocates within a cylinder and a piston ring or equivalent sealing means caused by the piston facilitates the sealing and, hence, the pumping action. Our invention is directly applicable to pumps of all pressure ranges from high pressure to low pressure.
An example of a high pressure application of our invention is the following specification: 350 pounds per square inch (PSI) pressure; 0.87 gallon per minute (GPM) flow rate (1 foot suction lift) at 1640 shaft revolutions per minute (R.P.M.), and applied electrical power of only 2.9 amperes at 90 volts; the foregoing very high efficiency unit, with its "low profile" shape or configuration, permits numerous utilizations not heretofore possible. For example a pump with the aforesaid specification may be incorporated into a portable cleaner for rugs, walls, ceilings, etc. wherein the cleaner comprises an electrically powered vacuum means and the total electrical power consumption of the cleaner is within the "normal" 15 ampere limit of a standard U.S. residential electrical power outlet.
An example of a prior art double acting simplex plunger pump is the series 5300 twin piston pump manufactured and sold by Hypro Division of Lear Siegler, Inc. of St. Paul, Minn. Although there are some similarities between the pump provided by our invention and the aforesaid Hypro pumps, there are a number of important differences. In particular the Hypro pump comprises a cast iron body, a relatively complex and expensive casting which includes two integral manifolds. Coacting with the cast iron body are a pair of cylinder heads which also are cast iron. Thus the Hypro unit has a total of three cast iron primary parts intended to coact with an internal double ended piston member driven by a crank on the end of a motor driven shaft.
Our invention has a unitary crankcase, a unitary manifold, two separate and unitary stuffing boxes, and two unitary heads comprising a total of six separate unitary parts adapted to be assembled together into a low profile unit unit for coaction with an internal double ended plunger member adapted to be reciprocated within the unit upon being driven by a crank on the end of a driven shaft. A very important feature of our invention is that the six aforesaid described unitary elements, i.e., the crankcase, manifold, stuffing boxes, and heads all are manufactured from extrusions; more specifically, all are slices taken at right angles to the longitudinal axis of an extrusion. The crankcase, for example, including a crankcase space, is simply and inexpensively defined by cutting a slice, i.e., a transverse cut of an extrusion, the outer configuration of which corresponds to the outer configuration of the crankcase body and with the crankcase space being defined during the extrusion process.
There are, of course, many prior art pumps. Examples include pumps disclosed in Pat. Nos. 4,232,063; 4,153,393; 4,721,444; 4,184,817 and 4,142,839. None of these patents, nor the above identified series 5300 Hypro pumps manufactured, nor any other pumps of which we are aware, provides a pump having the several advantages and unique features of our invention.